To plagiarize from SpaceWeather.com (an excellent site for astronomy buffs), "On August 1st, the entire Earth-facing side of the sun erupted in a tumult of activity. There was a C3-class solar flare, a solar tsunami, multiple filaments of magnetism lifting off the stellar surface, large-scale shaking of the solar corona, radio bursts, a coronal mass ejection and more."

Basically, the sun sloughed off a good chunk of its Earth-facing side a few days ago, and that leads to a deflection of our planet's magnetic field such that charged particles hit the atmosphere at much lower latitudes than normal. Effect, we get aurora (and satellite operators suffer miserably trying to keep their birds from cooking while still providing some basic level of service).